Wang, X., Jiang, Z., Jiang, S., Chang, J., Li, X., Wang, X., Zhu, L., 2020. Pore evolution and formation mechanism of organic-rich shales in the whole process of hydrocarbon generation: Study of artificial and natural shale samples. Energy &Fuels 32, 332-347.

https://doi.org/10.1021/acs.energyfuels.9b03789 Shale pore evolution has a dramatic influence on gas occurrence and is of great significance for the evaluation of gas shale reservoirs. To better understand the nanopore evolution during the whole hydrocarbon generation process, thermal simulation experiment, gas adsorption (N and CO ), and organic geochemistry experiments 2 2 were carried out. The results show that total pore volume (PV) and specific surface area (SSA) exist in two favorable development periods during the whole hydrocarbon generation process with corresponding vitrinite ∼ ∼ R reflectance ( ) values of 1.5 - 1.8% and 2.5 - 3.2%, respectively, which are two peak periods of porosity o development. In the two hydrocarbon generation intervals, primary organic matter (OM) and secondary OM crack to gases accompanied by the formation of OM-hosted pores in large quantities, resulting in the increase of porosity. Shale pore formation and evolution are dominantly controlled by hydrocarbon generation as well as diagenesis. Compaction and cementation exert destructive influences on mineral associated pores, especially in the relatively early diagenesis process, resulting in a great decrease of total porosity. Infilling of secondary OM to inorganic interparticle pores also results in the destruction of porosity. OM-hosted pores are documented as a function of thermal maturity, which is significantly related to kerogen and secondary OMcracking to hydrocarbon.

Wang, X., Li, W., Zhang, B., Pei, S., Chen, Z., 2019. The formation mechanisms of ultra-tight and overpressured gas reservoir in the third Member of Upper Triassic Xujiahe Formation in the northwestern Sichuan Basin. Natural Gas Industry 39, 25-35.

http://oversea.cnki.net/kcms/detail/detail.aspx?dbCode=cjfd&QueryID=14&CurRec=9&filename=TRQG20191 1009&dbname=CJFDLAST2019 In Chinese. More studies have been carried out on the tight and overpressured gas reservoir of the Upper Triassic Xujiahe Formation in the northwestern Sichuan Basin, but the formation mechanisms of tight reservoir, the distribution characteristics and formation mechanisms of abnormal ultra-high pressure and the effects of thermal evolution on large-scale tight gas accumulation have not been researched systematically and thoroughly. To this end, this paper studied the reservoir characteristics and main controlling factors of the third Member of Xujiahe Formation(Xu 3 Member for short) in this area using a large quantity of drilling data obtained recently. And combined with the thermal evolution of the source rocks and the evolution of diagenesis, the reasons for the formation of tight reservoir were analyzed. Then, the formation mechanisms of overpressured gas reservoirs were studied based on tectonic movement after the temperature and pressure characteristics of the fluids in gas reservoirs were analyzed. Finally, the mechanisms of large-scale overpressured natural gas accumulation were analyzed after the characteristics of large-scale overpressured gas reservoirs were summarized. And the following research results were obtained. First, ultra-tight reservoir of Xu 3 Member is the product under the joint effect of strong diagenetic compaction and strong calcareous cementation caused by a large amount of carbonate debris in sediments. Second, the Xu 3 Member reservoir has experienced high thermal evolution in great burial depth. The tightest reservoir is the area with the highest thermal evolution and also the main tight gas development area. The formation of ultra-high pressure tight gas reservoir is obviously affected by the strong diagenesis and the high thermal evolution in the late Cretaceous period. Third, in Jian'ge area, the diagenetic compaction of Xu 3 Member sandstone/glutenite leads to the reduction of porosity by 20%. The important reason for the reservoir densification caused by carbonate cementation is that Anxian tectonic movement leads to the uplifting of Longmenshan Mountain, providing sufficient sources of carbonate rocks for the deposit of Xujiahe Formation. And consequently, the porosity is reduced by 10-20%. Fourth, the formation of abnormal high pressure gas reservoir in the depression zone of this area is not caused by structural compression, but by poor pressure release resulted from fracture underdevelopment, hydrocarbon generation pressurization and tectonic reversal, which leads to the formation of an ultra-high pressure development zone of ultra-tight reservoir. The fracture development in the front margin of Longmenshan and Micangshan fault belts leads to pressure release, so it is a normal pressure zone, whose reservoir physical properties are better than those of the depression zone. It is concluded that the formation